In prior-art irons, water is heated and converted to steam by evaporation, the jets of steam emerging along the pressing face of the iron, e.g. through openings in a sole plate thereof.
In all appliances in which water is heated or evaporated, there is a formation of mineral deposits which can eventually obstruct the passages, outlets or other channels through which the steam or hot water passes. These mineral deposits are generally formed from water-insoluble calcium and magnesium salts, the residues of water evaporation or the like.
The deposits form predominantly at those locations at which the heat is applied to the water to be heated or evaporated and thus to the most strongly heated surfaces in contact with the water. In addition, the deposits form in the ducts, passages or tubes through which the steam is conducted.
In steam irons, this problem has necessitated, in a large number of cases, the use of distilled water from which such deposits will not form. Where other than distilled water is used, it is necessary to provide a demineralization or deposit-removal step after deposits have formed if the iron is to operate at its original efficiency or is to operate at all.
The use of distilled water is costly and a mechanical removal of the deposits cannot be achieved since access is not generally available to the chambers, ducts and passages in which the water is heated or converted to steam. As a consequence it has been necessary to use chemical demineralization techniques which are time consuming and not always effective. Furthermore, the demineralization agent is generally aggressive and corrosive and is detrimental to the health of the user. Finally, the disposal of the demineralizing agent constitutes a problem since it produces a strain on sewage-treatment facilities and the like.
If a demineralization is not carried out timely, the appliance fails and frequently cannot be repaired or freed from the deposit. In any case the deposition of mineral substances in heating chambers, ducts or channels reduces the useful life of the appliance by detrimentally affecting the seals and attacking the metallic parts thereof.
In a prior-art steam iron of the aforedescribed type, the evaporation chamber is provided with a flange which is set from below into the sole plate of the iron. The evaporation chamber or steam generator is thus readily removable for cleaning purposes and can, when cleaning is no longer possible, be replaced. This is also an expensive procedure and the device has been found to be disadvantageous in that deposits are found in the region of the steam passages as well as between the steam-generating chamber and the sole plate or member. These deposits cannot be eliminated by replacing the steam-generating chamber.